1. Field of the Invention
The present invention relates to an information processing device including a function for authenticating a person by reading the person's fingerprints such as a PDA (Personal Digital Assistant), a PHS (Personal Handy Phone System), a PC (Personal Computer), a handheld PC and other portable information terminals, and relates to a fingerprint detection structure in its fingerprint read part.
Mobile phone devices, as an example of information processing devices, are increasing range of uses by incorporating variety of applications and by processing various types of information and the like, which requires enhanced security protection such as personal information protection. Therefore, a mobile phone device includes a mechanism to lock its functions, and adopts measures such as releasing a locked state by using a previously registered password. The password uses symbols that can be entered via keys used for dial operation; and although easy to handle, users need to lock up or perform release operation and always have to remember the password. If the users forget the password or neglect to lock up or perform operation, then the security protection cannot be offered. Compared to such a method using passwords, authentication of a person through the person's fingerprint information is easy to handle with the expectation of higher security protection. Fingerprint information can be obtained by bringing a finger into contact with a fingerprint sensor mounted in the information processing device such as the mobile phone device.
2. Description of the Related Art
Among prior patent documents relating to authentication of a person by using the person's fingerprint information, for example, there are Japanese Patent Application Laid-Open Publication Nos. H05(1993)-95329, 2001-5951, 2002-49593, 2002-123821, 2002-185843, 2002-245443, 2001-510579, 2001-155137, 2002-330202, 2002-279412; United States Patent Application Publication Nos. US2001/0031074A1, US2002/0044675A1, US2002/0003892A1, U.S. Pat. No. 6,327,376B1 and others.
Japanese Patent Application Laid-Open Publication No. H05(1993)-95329 discloses a technology for preventing unauthorized use of other person's mobile phone by the verification of record data during transmittance/reception of the mobile phone. Japanese Patent Application Laid-Open Publication No. 2001-5951 discloses that a fingerprint recognition section includes a cover and static electricity of an operator is removed. Japanese Patent Application Laid-Open Publication No. 2002-49593 (United States Patent Application Publication No. US2001/0031074A1) discloses an authentication system using a display device having an optical living body recognition function in which authentication is performed by holding the palm of a hand to the display part; however this has a shortcoming of blocking the display with the palm of a hand. Japanese Patent Application Laid-Open Publication No. 2002-123821 (United States Patent Application Publication No. US2002/0044675A1) discloses only a fingerprint sensor including a cover and a technology to remove static electricity of an operator. Japanese Patent Application Laid-Open Publication No. 2002-185843 (United States Patent Application Publication No. US2002/0003892A1) discloses an information terminal device having a fingerprint recognition function by an optical sensing method. However, the amount of light from the light source has an influence on the sensitivity of a sensor, which causes more mounting space. Japanese Patent Application Laid-Open Publication No. 2002-245443 discloses a structure of a fingerprint image input device having a display function. However, the palm of a hand blocks the screen and the display function is impaired during detection. Japanese Patent Application Laid-Open Publication No. 2001-510579 (U.S. Pat. No. 6,327,376B1) discloses an electronic device mounting an optical sensing device using a transparent electrode. However, the amount of light passing through the transparent electrode has an influence on the sensitivity of a sensor, which causes more mounting space. Japanese Patent Application Laid-Open Publication No. 2001-510579 discloses only that a fingerprint sensor is mounted in the back of a battery pack of a mobile phone. Japanese Patent Application Laid-Open Publication No. 2002-330202 discloses nothing but a portable terminal device including a fingerprint sensor in the operation panel. Further, Japanese Patent Application Laid-Open Publication No. 2002-279412 discloses a mobile phone that reads fingerprints of a finger in an image sensor disposed in a main body through a slit formed adjacent to a display part. However, sliding fingers on the slit causes a part of skin or dust to enter into the slit, which has a risk of impairing the sensitivity of the sensor.
By the way, various types of information processing devices such as mobile phone devices are required of weight reduction and downsizing; tolerance to external factors such as shock, finger mark, sweat and moisture; ruggedness and durability; enhancement of security functions in order to store valuable personal information through a variety of functions provided therein; and convenience, design, safety functions as well since the devices are touched directly with a hand. Therefore, in order to realize and maintain security functions by detecting fingerprints, the detection function needs to be enhanced and protected.